Remove hacky double registration of to_here op in reg_distributed_ops (…

…pytorch#39602)

Summary:
Pull Request resolved: pytorch#39602

This was added as a part of
pytorch#38590 but we can use default arguments
here. We use fmt:;format to bind the default value to the rpc timeout at
runtime.
ghstack-source-id: 105983645

Test Plan: Ci

Differential Revision: D21912719

fbshipit-source-id: 7525c1322a95126f529301be142248af48565b82

test/backward_compatibility/check_backward_compatibility.py

@@ -95,6 +95,7 @@
     ('prim::min', datetime.date(2020, 6, 30)),
     ('prim::max', datetime.date(2020, 6, 30)),
     ('aten::to_here', datetime.date(2020, 6, 30)),
+    ('aten::to_here(RRef(t) self, double timeout*)', datetime.date(2020, 6, 30)),
     ('aten::local_value', datetime.date(2020, 6, 30)),
     ('aten::log', datetime.date(2020, 6, 30)),
     ('aten::__and__', datetime.date(2020, 6, 30)),

torch/csrc/jit/runtime/register_distributed_ops.cpp

@@ -10,6 +10,8 @@
 #include <torch/csrc/jit/runtime/register_ops_utils.h>
 #include <torch/library.h>
 
+#include <fmt/format.h>
+
 using at::Scalar;
 using at::Tensor;
 namespace dist_autograd = torch::distributed::autograd;
@@ -26,24 +28,9 @@ static auto workerInfo =
 
 RegisterOperators reg_rpc_ops(
     {Operator(
-         "aten::to_here(RRef(t) self) -> t(*)",
-         [](Stack& stack) {
-           auto rref = pop(stack).toRRef();
-           IValue res;
-           if (rref->isOwner()) {
-             res =
-                 c10::dynamic_intrusive_pointer_cast<dist_rpc::OwnerRRef>(rref)
-                     ->getValue();
-           } else {
-             res = c10::dynamic_intrusive_pointer_cast<dist_rpc::UserRRef>(rref)
-                       ->toHere();
-           }
-           push(stack, std::move(res));
-           return 0;
-         },
-         aliasAnalysisFromSchema()),
-     Operator(
-         "aten::to_here(RRef(t) self, double timeout) -> t(*)",
+         fmt::format(
+             "aten::to_here(RRef(t) self, float timeout = {}) -> t(*)",
+             torch::distributed::rpc::kDefaultRpcTimeoutSeconds),
          [](Stack& stack) {
            auto timeout = pop(stack).toDouble();
            auto rref = pop(stack).toRRef();